The translation of isolated C4 m-RNA on rabbit reticulocyte polysomes will be examined in both normal and C4-deficient guinea pigs to determine the mechanism for failure to synthesize complete pro C4. The synthesis of C5 will be studied in epithelial and mesenchymal cells to resolve the controversy generated by recent discrepant reports in the literature. The mechanism of cleavage of pro complement proteins to their serum counterparts will be studied in guinea pig macrophages and human monocytes.